One aim of this project is to assess the effects of prenatally acquired familiarity with the maternal voice in a task where newborns can learn to gain access to either their mother's voice or the voice of another woman, but are forced to use only their left or right ear. It is expected that the known maternal voice preference will be greater for infants who use their left ear. The second aim is to assess the effects of prenatally acquired familiarity with the mother's language in a task where newborns can learn to gain access to the familiar language or an unfamiliar language, bur can use only one ear. It is expected that the known preference for familiar language will be greater for infants using their right ear. These finding would directly indicate that the very early functional lateralization of auditory perception and auditorily-mediated cognition is not driven only by maturational processes but is also influenced by prenatal auditory experiences. In brief, the data would indicate that the very early development of the substrates that permit the ready development of the uniquely human ability to use and understand language is also influenced by environmental factors. These data would be of interest to the disciplines of developmental neuroscience, cognitive development, hearing and communication science, phycholinguistics, and also to the clinical disciplines interested in the developmental disorders affecting hearing, communication and learning.